Black background in my thumbnails?!?!

When I generates thumnails like this:

PHP Code:

---

$save = $targetPath."thumb_" . $imagepath; //This is the new file you saving
$file = $targetPath."".$imagepath; //This is the original file

list($width, $height) = getimagesize($file) ; 

if($width > $height){
    $modwidth = 90;
    $diff = $width / $modwidth;
    $modheight = $height / $diff;
} else {
    $modheight = 90;
    $diff = $height / $modheight;
    $modwidth = $width / $diff;
}

$diff = $width / $modwidth;

$modheight = $height / $diff; 
$tn = imagecreatetruecolor($modwidth, $modheight) ; 
$image = imagecreatefromjpeg($file) ; 
imagecopyresampled($tn, $image, 0, 0, 0, 0, $modwidth, $modheight, $width, $height) ; 

imagejpeg($tn, $save, 100); 


---

... it comes out with a black background... Is it possible to make this background white or even better, transparent?

Thanks...

It doesn't make sense to me, because if you are making thumbnail with the same aspect ratio as the original image, you shouldn't see the black border at all.

Nevertheless, maybe you can find those functions helpful:
Alpha blending: http://si2.php.net/manual/en/functio...hablending.php
Filling image with solid color: http://si2.php.net/manual/en/function.imagefill.php